Extracted ObjCARCContract from ObjCARCOpts into its own file.

This also required adding 2x headers Dependency Analysis.h/Provenance Analysis.h
and a .cpp file DependencyAnalysis.cpp to unentangle the dependencies inbetween
ObjCARCContract and ObjCARCOpts.

llvm-svn: 173760

1 files changed, 79 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/ObjCARC/ProvenanceAnalysis.h b/llvm/lib/Transforms/ObjCARC/ProvenanceAnalysis.h
new file mode 100644
index 00000000000..d86f08b7481
--- /dev/null
+++ b/llvm/lib/Transforms/ObjCARC/ProvenanceAnalysis.h
@@ -0,0 +1,79 @@
+//===- ProvenanceAnalysis.h - ObjC ARC Optimization ---*- mode: c++ -*-----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file declares a special form of Alias Analysis called ``Provenance
+/// Analysis''. The word ``provenance'' refers to the history of the ownership
+/// of an object. Thus ``Provenance Analysis'' is an analysis which attempts to
+/// use various techniques to determine if locally
+///
+/// WARNING: This file knows about certain library functions. It recognizes them
+/// by name, and hardwires knowledge of their semantics.
+///
+/// WARNING: This file knows about how certain Objective-C library functions are
+/// used. Naive LLVM IR transformations which would otherwise be
+/// behavior-preserving may break these assumptions.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
+#define LLVM_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
+
+#include "llvm/ADT/DenseMap.h"
+
+namespace llvm {
+  class Value;
+  class AliasAnalysis;
+  class PHINode;
+  class SelectInst;
+}
+
+namespace llvm {
+namespace objcarc {
+/// \brief This is similar to BasicAliasAnalysis, and it uses many of the same
+/// techniques, except it uses special ObjC-specific reasoning about pointer
+/// relationships.
+///
+/// In this context ``Provenance'' is defined as the history of an object's
+/// ownership. Thus ``Provenance Analysis'' is defined by using the notion of
+/// an ``independent provenance source'' of a pointer to determine whether or
+/// not two pointers have the same provenance source and thus could
+/// potentially be related.
+class ProvenanceAnalysis {
+  AliasAnalysis *AA;
+
+  typedef std::pair<const Value *, const Value *> ValuePairTy;
+  typedef DenseMap<ValuePairTy, bool> CachedResultsTy;
+  CachedResultsTy CachedResults;
+
+  bool relatedCheck(const Value *A, const Value *B);
+  bool relatedSelect(const SelectInst *A, const Value *B);
+  bool relatedPHI(const PHINode *A, const Value *B);
+
+  void operator=(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
+  ProvenanceAnalysis(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
+
+public:
+  ProvenanceAnalysis() {}
+
+  void setAA(AliasAnalysis *aa) { AA = aa; }
+
+  AliasAnalysis *getAA() const { return AA; }
+
+  bool related(const Value *A, const Value *B);
+
+  void clear() {
+    CachedResults.clear();
+  }
+};
+
+} // end namespace objcarc
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H